This invention relates to internal combustion engines, and is more particularly directed to an engine of the type having a pair of rotors mounted to rotate in a pair of adjacent cylinders in a housing, about parallel axles supported in the housing. Each rotor is provided with a plurality of lobes, whereby the lobes intermesh during rotation of the axles to form varying volume chambers. The lobes of the rotors have cycloidal shapes.
German Offenlegungsschrift No. 1,751,460 discloses an internal combustion engine having three working elements. Two of these elements are rotatable about parallel axes, and the other element is stationary and supports the axles of the rotors and defines a pair of cylinders. The axes of the cylinders coincide with the rotating axes of the axles of the rotors. In this arrangement all of the contours of a working chamber are defined by lines or rather surfaces along which the individual engine elements cooperate with each other. Sealing means provide a continuous seal of said surfaces. Each of these elements is maintained in direct contact with the corresponding surfaces of another element.
The manufacturing expenses of this known engine are rather high. In addition, this engine has the disadvantage that its efficiency is reduced due to the frictional forces between the cooperating elements.
German Offenlegungsschrift No. 2,123,530 discloses a rotary piston engine comprising helical gears for a compressible medium. In this arrangement the flank profile of the rib head has an epicycloidal section, which merges into an extended hypocycloid.
The generating circle of the epicycloid has a radius greater than half the height of the rib head of the meshing rotors, said radius of said generating circle, however, being smaller than half the radius of the revolving circle of the intermeshing rotors. This engine also has the disadvantage that its efficiency is substantially reduced as a result of the friction forces between the meshing gears.
Further similar arrangements are disclosed, for example, in French Pat. No. 1,520,471 and in U.S. Pat. No. 3,115,124. In the French Pat. No. 1,520,471 the engine comprises four lobed or gear rotors which rotate in the cylinders of a housing.
German Offenlegungsschrift No. 2,057,475 discloses an internal combustion engine having a pair of lobed rotors mounted in a housing for rotation in opposite directions. The rotors are rigidly secured to their respective bearing rotating shafts. Each rotor is provided with a plurality of blades or lobes having the form of cycloids. The outer extremeties of the blades or lobes run along the inner wall of the housing, and the lobes of the rotors form variable volume chambers, as a result of their rotation. These chambers are defined by the lobes of the rotors, as well as by the inner wall of the housing. The housing is also provided with an intake port for the fuel mixture, as well as with an outlet port for exhaust gases.